Storage control device and control method therefor

ABSTRACT

A storage control device comprises: a first I/O control unit for controlling read/write of data from/to one or more HDDs (Hard Disk Drives); a second I/O control unit whose current consumption is approximately equal to that of the first I/O control unit; two or more first power supply devices supplying electric power to the first I/O control unit; two or more second power supply devices supplying electric power to the second I/O control unit; and at least three circuit breakers receiving electric power supplied from outside and supplying the electric power to the first and second power supply devices while interrupting the supply of the electric power when current exceeding a preset level passes. Each of the first/second power supply devices includes a current balancing circuit for equalizing output currents of the first/second power supply devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of application Ser. No.10/765,165, filed Jan. 28, 2004 now U.S. Pat. No. 7,096,372, whichclaims priority of Japanese Patent Application No. 2003-396282, filedNov. 26, 2003, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a storage control device forcontrolling a storage device, and a control method for the storagecontrol device.

Today, information processing systems are playing a highly importantrole in business activities and above all, storage devices such as diskarrays for storing vast amounts of data as corporate assets areextremely important. Therefore, multi-level security measures are takenfor protecting data stored in such storage devices. For example, in astorage control device of a storage device for controlling the operationof the whole storage device, many of internal electronic devices (powerinlet devices such as breakers, power supplies, control devices,electric cables, etc.) are duplexed for redundancy and therebyexceedingly high reliability and availability are realized.

An example of such a storage device is disclosed in JP-A-2002-34177, forexample.

SUMMARY OF THE INVENTION

In this case, each of the redundant (duplicated) power inlet devices hasto have enough capacity for receiving the power to be consumed by thewhole storage device. Further, electric current consumption of storagedevices is increasing in recent years as a result of their increasingperformance, by which the power inlet devices are more and more requiredto have larger electric power capacity.

In the case where the storage device is equipped with large-capacitypower inlet devices, the capacity of power supply equipment of the placewhere the storage device is installed also needs to be increased.Increasing the capacity of the power supply equipment requireselectrical work to the facilities (replacement/addition of a powerswitchboard, electric cables, etc.). As a measure for avoiding suchelectrical work, it is possible to partition each power inlet device ofthe storage device into a plurality of small-capacity power inletdevices. However, the increase of the number of power inlet devicescauses upsizing of the storage device, increased complexity of thedevice, and an increase in the cost.

It is therefore the primary object of the present invention to provide astorage control device and a control method for the storage controldevice capable of resolving the above problems.

In accordance with an aspect of the present invention, there is provideda storage control device comprising: a first I/O control unit includinga channel control unit being connected with an information processingdevice to communicate data and receiving a data I/O request from theinformation processing device, a disk control unit being connected withone or more HDDs (Hard Disk Drives) storing data and reading/writingdata from/to the HDDs according to the data I/O request, a cache memoryfor storing data communicated between the channel control unit and thedisk control unit, and a connection unit interconnecting the channelcontrol unit, the disk control unit and the cache memory to communicatedata; a second I/O control unit whose current consumption isapproximately equal to that of the first I/O control unit; two or morefirst power supply devices supplying electric power to the first I/Ocontrol unit; two or more second power supply devices supplying electricpower to the second I/O control unit; and at least three circuitbreakers receiving electric power supplied from outside and supplyingthe electric power to the first and second power supply devices whileinterrupting the supply of the electric power when current exceeding apreset level passes. Each of the first/second power supply devicesincludes a current balancing circuit for equalizing output currents ofthe first/second power supply devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become moreapparent from the consideration of the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view showing the overall composition of astorage device (disk array device) in accordance with an embodiment ofthe present invention;

FIGS. 2A and 2B are perspective views showing the overall composition ofa control device of the storage device of the embodiment;

FIG. 3 is a perspective view showing the overall composition of a drivedevice of the storage device of the embodiment;

FIG. 4 is a perspective view showing control module boxes (logicmodules) being stored in the control device of the embodiment;

FIG. 5 is a perspective view showing HDD boxes (HDD modules) beingstored in the drive device of the embodiment;

FIG. 6 is a block diagram showing the internal composition of thestorage device of the embodiment;

FIG. 7 is a block diagram showing the connection of a disk adapter ofthe storage device to HDDs through a communication link;

FIG. 8 is a block diagram showing the mechanism of power supply of thestorage device of the embodiment;

FIG. 9 is a block diagram showing the mechanism of power supply of thestorage device of the embodiment;

FIG. 10 is a block diagram showing power supply to device loads of astorage device;

FIG. 11 is a block diagram showing power supply to device loads of astorage device;

FIG. 12 is a block diagram showing power supply to device loads of astorage device;

FIG. 13 is a block diagram showing power supply to device loads of thestorage device according to the embodiment;

FIG. 14 is a block diagram showing power supply to device loads of thestorage device according to the embodiment;

FIG. 15 is a block diagram showing the mechanism of power supply of thestorage device of the embodiment;

FIG. 16 is a flow chart showing the operation of current balancingcircuits for controlling and equalizing DC output currents of AC/DCpower supplies of the storage device;

FIG. 17 is a block diagram showing the mechanism of power supply of thestorage device of the embodiment;

FIG. 18 is a circuit diagram showing an example of the composition of anAC box of the storage device for three-phase AC power; and

FIG. 19 is a circuit diagram showing an example of the composition of anAC box of the storage device for single-phase AC power.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring now to the drawings, a description will be given in detail ofpreferred embodiments in accordance with the present invention.

[Overall Composition of Disk Array Device]

First, the overall composition of a storage device 100 (hereinafter alsoreferred to as “disk array device 100”) in accordance with an embodimentof the present invention will be described referring to FIG. 1. The diskarray device 100 shown in FIG. 1 comprises a control device 110 (storagecontrol device) and one or more drive devices 120. In the example ofFIG. 1, the control device 110 is placed at the center of the disk arraydevice 100, and the drive devices 120 are placed on both sides of thecontrol device 110.

The control device 110 controls the operation of the whole disk arraydevice 100. While details will be explained later, the control device110 contains logic units 420 (for controlling the whole disk arraydevice 100) and HDD (Hard Disk Drive) units 310 (for storing data) inits front part and rear part. Meanwhile, each drive device 120 containsHDD units 310 in its front part and rear part.

In the disk array device 100, a variety of electronic devices areinstalled with high packing density in order to attain both high storagecapacity and downsizing. Although not shown in FIG. 1, AC power issupplied from external power supply equipment (e.g. power switchboard1100) to the control device 110 and the drive devices 120 for enablingthe electronic devices. In the following, detailed composition of thecontrol device 110 and the drive device 120 will be described referringto FIG. 2A through FIG. 5.

[Control Device]

FIGS. 2A through 4 are perspective views showing the composition of thecontrol device 110. FIG. 2A and FIG. 2B view the control device 110 fromits right front and left rear, respectively.

The control device 110 contains HDD modules 300, logic modules 400,batteries 800, AC boxes (circuit breakers) 700, AC/DC power supplies(power supply devices) 600, fans 500 and an operator panel 111 in itscabinet 200.

The HDD modules 300 are stored in the upper part of the cabinet 200. Ineach HDD module 300, a plurality of HDD units 310 for storing data aredetachably installed in rows and a plurality of fiber channel switches150 (hereinafter also referred to as “FSWs 150”) are also installeddetachably.

Each HDD unit 310 includes an HDD (Hard Disk Drive) 311 for storingdata, a DC-DC converter, a control circuit, etc. which are stored in acanister. The DC-DC converter receives the DC power (rated voltage: 56V)supplied from the AC/DC power supply 600 to the HDD unit 310, convertsthe rated voltage 56V of the DC power into 5V and 12V, and supplies theconverted DC power to the HDD 311, the control circuit, etc. The 12V DCpower is supplied to, for example, a motor which spins disks of the HDD311. The 5V DC power is supplied to, for example, the control circuitwhich reads/writes data from/to the HDD 311.

The logic modules 400 are stored in the middle part of the cabinet 200.Each logic module 400 includes a logic unit 420 and a plurality of logicmodule fans 410. The logic unit 420 includes a plurality of controlcircuit boards 430 having various functions for reading/writing datafrom/to the HDDs 311. While details will be described later, eachcontrol circuit board 430 of the logic unit 420 includes at least oneselected from a channel adapter (channel control unit) 131, a cachememory 133, a shared memory 135, a connection unit 132 and a diskadapter (disk control unit) 134. On the control circuit board 430, aplurality of electronic circuits (operating at various voltages) and aDC-DC converter (for generating the various voltages from the 56V DCpower supplied from the AC/DC power supply 600) are formed. Each of thechannel adapter 131, cache memory 133, shared memory 135, connectionunit 132 and disk adapter 134 is duplexed for redundancy in order toincrease the reliability of the disk array device 100. Thus, a first I/Ocontrol unit is formed by a first channel adapter 131, first cachememory 133, first shared memory 135, first connection unit 132 and firstdisk adapter 134, while a second I/O control unit is formed by a secondchannel adapter 131, second cache memory 133, second shared memory 135,second connection unit 132 and second disk adapter 134. Currentconsumption of the first I/O control unit is substantially equal to thatof the second I/O control unit. Hereinafter, the channel adapter 131,cache memory 133, shared memory 135, connection unit 132 and diskadapter 134 will also be referred to as “I/O control unit”. Of coursethe I/O control unit does not have to include all the above components.The I/O control unit may be built up in any composition as long as itcan realize the functions for reading/writing data from/to the HDDs 311in response to data I/O requests supplied from an information processingdevice 1000. The logic module fans 410 supply cooling air to the logicunit 420. The cooling air taken in the cabinet 200 enters a logic module400 from its front through gaps between the control circuit boards 430of the logic unit 420, cools the logic unit 420, and is dischargedthrough the top of the cabinet 200 by the sucking force of the logicmodule fans 410 and the fans 500.

The batteries 800, the AC boxes 700 and the AC/DC power supplies 600 arestored in the lower part of the cabinet 200. Hereinafter, the batteries800, AC boxes 700 and AC/DC power supplies 600 will also be referred toas “power supply module”. The mechanism for power supply to the diskarray device 100 of this embodiment is shown in FIGS. 8, 9 and 15.

Each AC box 700, serving as an electric power intake of the disk arraydevice 100, is provided with a breaker 710. The AC box 700 is suppliedwith AC power from the power supply equipment (e.g. power switchboard1100) which is set up outside the disk array device 100. The AC powersupplied to the AC box 700 may either be three-phase AC power orsingle-phase AC power. The AC power supplied to the AC box 700 fromoutside the disk array device 100 is then supplied to the AC/DC powersupply 600 through an electric cable detachably connecting the AC box700 and the AC/DC power supply 600. Since the AC box 700 has the breaker710, the supply of power to the AC/DC power supply 600 is interrupted bythe breaker 710 when the current passing through the breaker 710 exceedsa preset level. Examples of the composition of the AC box 700 are shownin FIGS. 18 and 19, in which FIG. 18 shows an AC box 700 that issupplied with three-phase AC power and FIG. 19 shows an AC box 700 thatis supplied with single-phase AC power. As seen from the figures, thedisk array device 100 of this embodiment can easily be adapted to boththree-phase AC power and single-phase AC power depending on the type ofthe power supply equipment (e.g. power switchboard 1100) of the user, byreplacing the AC box 700 and the electric cables detachably connectingthe AC box 700 and the AC/DC power supplies 600.

The AC/DC power supply 600, including an AC-DC conversion unit 610 forconverting the AC power to DC power, is a power supply device forsupplying DC power to the I/O control unit of the logic unit 420, theHDD units 310, etc. The AC/DC power supply 600 further includes acurrent balancing circuit 620. The current balancing circuits 620 of theAC/DC power supplies 600 are connected together by a rear circuit board450 (hereinafter also referred to as “backboard 450”), by which the DCoutput currents of the AC/DC power supplies 600 are equalized with oneanother. The operation of the current balancing circuit 620 forcontrolling and equalizing the DC output currents is shown in a flowchart of FIG. 16. FIG. 16 shows a case where DC output currents of twoAC/DC power supplies 600 are equalized with each other. Incidentally,the two AC/DC power supplies 600 are abbreviated as “PS1” and “PS2” inFIG. 16.

First, when the output current of PS1 is larger than that of PS2 (YES inS1000), PS2 detects a maximum current signal of PS1 from a PSCONT signalsupplied thereto (S1001). The PSCONT signal is communicated through, forexample, a circuit that interconnects the current balancing circuits 620via the backside circuit board 450. Subsequently, PS2 compares themaximum current signal with its own current signal (S1002) and increasesits output voltage by an amount corresponding to the difference betweenthe maximum current signal and the own current signal (S1003), by whichthe output current of PS2 increases (S1004), the output current of PS1decreases (S1005), and thereby the output currents of PS1 and PS2 arebalanced and equalized with each other (S1006). On the other hand, whenthe output current of PS1 is not larger than that of PS2 (NO in S1000),PS1 detects a maximum current signal of PS2 from a PSCONT signalsupplied thereto (S1007). Subsequently, PS1 compares the maximum currentsignal with its own current signal (S1008) and increases its outputvoltage by an amount corresponding to the difference between the maximumcurrent signal and the own current signal (S1009), by which the outputcurrent of PS1 increases (S1010), the output current of PS2 decreases(S1011), and thereby the output currents of PS1 and PS2 are balanced andequalized with each other (S1012).

The current balancing circuit 620 is capable of not only equalizing theoutput currents of the AC/DC power supplies 600 but also setting theratio among the output currents at a particular ratio. The setting ofthe output current ratio can be done by inputting a balance settingsignal to the current balancing circuits 620. The balance setting signalmay be inputted to the current balancing circuits 620 by the operator ofthe disk array device 100 (who maintains and manages the disk arraydevice 100) by turning a volume knob (trimmer) on the disk array device100, for example. The balance setting signal may also be implemented asa control signal that is supplied from a management terminal 136(explained later). Inputting the balance setting signal to each AC/DCpower supply 600 makes it is possible, for example, to set the outputcurrent ratio of two AC/DC power supplies 600 to 2:1.

FIG. 15 shows the mechanism of power supply when three-phase AC power issupplied to the AC box 700. In this example, the AC box 700 has abreaker 710 for each phase (R, S, T) of the three-phase AC power. Whenthe current of a phase exceeds a preset level, power supply of the phaseis interrupted by the breaker 710. The AC/DC power supply 600 isprovided with an AC-DC conversion unit 610 for each phase (R, S, T). Thecurrent balancing circuit 620 controls the DC output current so as toequalize the DC output currents of the AC/DC power supplies 600 as wellas equalizing output currents of the three phases R, S and T. Thecomposition of the AC/DC power supply 600 of FIG. 15 can be used forboth three-phase AC power and single-phase AC power. For three-phase ACpower, each of the three AC-DC conversion units 610 of the AC/DC powersupply 600 converts the AC power of each phase (R, S, T) into DC powerrespectively. For single-phase AC power, each AC-DC conversion unit 610converts each input AC power into DC power. Also in the case ofsingle-phase AC power, the current balancing circuit 620 controls the DCoutput current so as to equalize the DC output currents of the AC/DCpower supplies 600 as well as equalizing output currents of the threelines.

Each electronic device such as the I/O control unit of the logic unit420, the HDD unit 310 and the fiber channel switch 150 is a “deviceload” that consumes the power supplied from the AC/DC power supply 600.The electronic devices as the device loads (logic unit 420, HDD unit310, etc.) consume DC power of different rated voltages. For example,the control circuit board 430 of the logic unit 420 of this embodimentconsumes DC power of a rated voltage of 5V, 3.3V or the like, while therated voltage of the HDD unit 310 is 12V or 5V and that of the fiberchannel switch 150 is 5V. For this reason, the DC-DC converter forconverting DC voltage is provided to the control circuit boards 430, HDDunit 310s, etc. of this embodiment, and DC power of a single ratedvoltage is supplied to the device loads (control circuit boards 430, HDDunits 310, etc.).

Concretely, the AC/DC power supply 600 receives 200V AC power andconverts it into 56V DC power. The DC-DC converter of each device load(control circuit boards 430, HDD units 310, etc.) generates theparticular voltage (12V, 5V, etc.) from the single input voltage of 56V.Incidentally, the voltages mentioned above are only examples and can ofcourse be altered.

The battery 800 is a storage battery for supplying electric power to theDC-DC converter of each device (HDD 311, control circuit board 430,etc.) of the control device 110 in place of the AC/DC power supply 600in case of interruption of power supply from the AC/DC power supply 600due to blackout, failure of the AC/DC power supply 600, etc.

The operator panel 111, provided to the front of the cabinet 200, is adevice for receiving inputs from the operator maintaining and managingthe disk array device 100.

The rear circuit board (backboard) 450 is a circuit board having acircuit for electrically interconnecting the logic units 420, HDD units310 and the power supply module.

[Drive Device]

FIGS. 3 and 5 are perspective views showing the composition of the drivedevice 120, in which FIG. 3 views the drive device 120 from its rightfront. The drive device 120 contains HDD modules 300, batteries 800, ACboxes 700, AC/DC power supplies 600 and fans 500 in its cabinet 200 inthe shape of a rectangular parallelepiped. Each component (300, 500,700, 800) of the drive device 120 is the same as that of the controldevice 110. The cabinet 200 of the control device 110 and that of thedrive device 120 can be formed in the same structure. In this case, thecontrol device 110 can be built up by storing the logic modules 400 inthe middle part of the cabinet 200, while the drive device 120 can bebuilt up by storing the HDD modules 300 in the middle part.

[Composition of Disk Array Device]

FIG. 6 is a block diagram showing the internal composition of the diskarray device 100 of this embodiment. The disk array device 100 isconnected with the information processing devices 1000 via a SAN(Storage Area Network) 900 to communicate data.

The information processing device 1000 is information equipment (e.g.computer) including a CPU (Central Processing Unit) and memory. Variousprograms are run by the CPU of the information processing device 1000and thereby a variety of functions are realized. The informationprocessing device 1000 may be used as, for example, a centric computerof an automatic cash dispenser system for a bank, a seat reservationsystem for an airline company, etc. The disk array device 100, which maystore business data of such social and public importance, is requiredextremely high reliability.

The SAN 900 is a network for communicating data between the informationprocessing device 1000 and the disk array device 100. The communicationbetween the information processing device 1000 and the disk array device100 via the SAN 900 is executed typically according to the fiber channelprotocol. The information processing device 1000 transmits data I/Orequests to the disk array device 100 by the fiber channel protocol.

The disk array device 100 of this embodiment includes a disk arraycontrol module 130 and disk array drive modules 140. The disk arraycontrol module 130 is formed in the control device 110, while the diskarray drive modules 140 are formed in the control device 110 or drivedevice 120. In other words, the control device 110 includes the diskarray control module 130 and the disk array drive modules 140, while thedrive device 120 includes the disk array drive modules 140.

The disk array control module 130 receives a data I/O request from aninformation processing device 1000 and reads/writes data from/to an HDD311 of a disk array drive module 140 according to the received data I/Orequest. The disk array control module 130 includes the channel adapters131, cache memory 133, connection unit 132, shared memory 135, diskadapters 134 and management terminal 136 (hereinafter, also referred toas “SVP 136”). Each of the channel adapter 131, cache memory 133,connection unit 132, shared memory 135 and disk adapter 134 isimplemented by the control circuit board 430 constituting the logic unit420 which has been shown in FIG. 4.

Each channel adapter 131 is connected to the information processingdevices 1000 to communicate data. The channel adapter 131 receives adata I/O request from an information processing device 1000 according tothe fiber channel protocol for example, and communicates data with theinformation processing device 1000.

The cache memory 133 and the shared memory 135 are memory for storingdata and commands that are communicated between the channel adapters 131and the disk adapters 134. For example, when the data I/O request thatthe channel adapter 131 receives from the information processing device1000 is a read request, the channel adapter 131 writes the write requestto the shared memory 135 while writing write data received from theinformation processing device 1000 to the cache memory 133, by which adisk adapter 134 reads the write data from the cache memory 133according to the write request stored in the shared memory 135 andwrites the write data to an HDD 311.

The connection unit 132 interconnects the channel adapters 131, sharedmemory 135, cache memory 133 and disk adapters 134 to communicate data.The connection unit 132 is implemented by, for example, a crossbarswitch.

Each disk adapter 134 is connected to the HDDs 311 storing data. Thedisk adapter 134 communicates with the HDDs 311 according to the dataI/O requests and thereby reads/writes data from/to the HDDs 311. Thedata read/write is done through, for example, a communication linkconstituting a loop specified by the FC-AL of the fiber channelstandards (hereinafter, also referred to as “FC-AL loop”). Thecommunication link is formed to include the disk adapter 134,communication cables 160, FSWs 150 and HDDs 311. The communicationbetween the disk adapter 134 and the HDD 311 is relayed by the FSW(Fiber channel Switch) of the disk array drive module 140.

The management terminal 136 is information equipment for maintaining andmanaging the disk array device 100. The management terminal 136 can beimplemented by, for example, a foldable notebook computer having adisplay and a keyboard. The management terminal 136 is stored in thecontrol device 110. Of course it is also possible to place themanagement terminal 136 outside the control device 110. For example, themanagement terminal 136 may be implemented by a computer at a remotelocation which is connected to the control device 110 via acommunication network. The type of the computer is not limited tonotebook computers but other types (desktop computer, etc.) can be usedfor the management terminal 136. The management terminal 136 may eitherbe implemented as a special-purpose information processing deviceexclusively for the maintenance/management of the disk array device 100or a general-purpose information processing device to which themaintenance/management functions for the disk array device 100 areadded.

Incidentally, the channel adapters 131, disk adapters 134, cache memory133, shared memory 135 and connection unit 132 which are shownseparately in FIG. 6 may also be formed integrally. It is also possibleto form part of the components integrally.

[Fiber Channel Switch (FSW)]

FIG. 7 is a block diagram showing the connection of the disk adapter 134to the HDDs 311 through the communication link constituting the FC-ALloop. As shown in FIG. 7, the FC-AL loop can be formed by connecting thedisk adapter 134 and the HDDs 311 to multiplexers 151 of the FSW 150. Inthe example of FIG. 7, an FC-AL loop is formed across two FSWs 150.

The “selection signal” supplied to each multiplexer 151 is a signal forselecting one of the two input terminals (“0” and “1”) of themultiplexer 151. A selection signal designating the input terminal “1”is supplied to a multiplexer 151 when a disk adapter 134 or HDD 311 isconnected to the multiplexer 151, while a selection signal designatingthe input terminal “0” is supplied when no device is connected to themultiplexer 151. When a failure occurring to an HDD 311 is detected, theselection signal designating the input terminal “0” is supplied to themultiplexer 151 connected to the HDD 311. The selection signals suppliedto the multiplexers 151 are controlled by a control unit 152, forexample.

In addition to the multiplexers 151, the FSW 150 is further providedwith the control unit 152 and a DC-DC converter 153.

The control unit 152 controls the FSWs 150 and the DC-DC converters ofthe HDD units 310. The control of the FSWs 150 includes the control ofthe selection signal supplied to each FSW 150. The control unit 152controls the selection signal when an HDD 311 is set to a state capableof communicating with the disk adapter 134, when the communication of anHDD 311 with the disk adapter 134 is disabled, etc.

The DC-DC converter 153 converts the 56V DC power supplied from theAC/DC power supply 600 into DC power for the FSW 150 (e.g. 5V DC power).

[Mechanism of Power Supply]

Next, the mechanism of power supply to the disk array device 100 will beexplained. Since the disk array device 100 is required extremely highreliability as mentioned before, the power supply to the disk arraydevice 100 is duplexed for redundancy as shown in FIG. 10. Concretely,each of the redundant (duplexed) AC boxes 700 supplies power toredundant AC/DC power supplies 600 which are redundantly provided toeach device load (Each device load is provided with the same number ofredundant AC/DC power supplies 600.). In this case, the AC boxes 700 areconnected so as to supply power to different AC/DC power supplies 600,by which the control of the disk array device 100 can be maintained evenin case of failure occurring to an AC box 700, AC/DC power supply 600 ordevice load. The disk array device 100 of FIG. 10 has two AC boxes 700,for example. Even when the breaker 710 of one of the AC boxes 700 tripsand thereby power supply is interrupted, the power supply to theelectronic devices of the disk array device 100 is continued by anotherAC box 700. In order to realize such composition, each device load ofthe disk array device 100 is provided with the same or larger number ofAC/DC power supplies 600 (for supplying power thereto) than the AC boxes700. Like FIG. 9, in the arrangement of FIG. 10, each of the AC/DC powersupplies 600 is formed by an AC-DC conversion unit 610 and a currentbalancing circuit 620 so as to equalize the output currents of the AC/DCpower supplies 600, and further a backboard 450 is provided. Further,like FIG. 9, the current balancing circuit 620 is capable of not onlyequalizing the output currents of the AC/DC power supplies 600 but alsosetting the ratio among the output currents at a particular ratio.Further, although not shown in the drawings, in the arrangement of eachof FIGS. 11 to 14, each of the AC/DC power supplies 600 is formed by anAC-DC conversion unit 610 and a current balancing circuit 620 so as toequalize the output currents of the AC/DC power supplies 600, andfurther a backboard 450 is provided.

In the case where the breaker 710 of one of the AC boxes 700 trips andthereby power supply is interrupted, current for covering powerconsumption of both the device loads #1 and #2 passes through the otherAC box 700. Assuming the current consumption of each device load #1, #2of the example of FIG. 10 is 15 A, current as high as 30 A may passthrough the breaker 710 of each AC box 700. Therefore, a breaker 710that can stand (without tripping) at least 30 A has to be used for eachAC box 700 of the disk array device 100 of FIG. 10. In this case, thepower switchboard 1100 is of course required to have high capacity forwithstanding such high current.

The current consumption also increases when the disk array device 100 isscaled up (e.g. when the HDD units 310 or disk adapters 134 areincreased for enlarging storage capacity of the disk array device 100).For example, if we assume that the current consumption of each deviceload #1, #2 increased to 30 A as shown in FIG. 11, the breaker 710 ofeach AC box 700 has to be replaced with one that can withstand at least60 A, and the same applies to the power switchboard 1100. Themodification of the AC box 700 for attaining high current-carryingcapacity (replacing the AC box 700, cables, etc.) is relatively easy,whereas increasing the current-carrying capacity of the powerswitchboard 1100 requires electrical work to the facilities which is noteasy. Further, the increase of current-carrying capacity of the powerswitchboard 1100 might require modification of contract with theelectric power company and it might increase electricity charges andrunning cost of the disk array device 100.

As a measure for scaling up the disk array device 100 without increasingthe current-carrying capacity of the AC box 700 and the powerswitchboard 1100, it is possible to implement each AC box 700 in FIG. 11by two AC boxes 700 as shown in FIG. 12. In FIG. 12, the AC box #1 inFIG. 11 is implemented by two AC boxes #1 and #3, and the AC box #2 inFIG. 11 is implemented by two AC boxes #2 and #4. By such composition,the current-carrying capacity of each AC box 700 can be kept down at 30A.

In the disk array device 100 of this embodiment, it is possible toreduce the current-carrying capacity of each AC box 700 to 20 A as shownin FIG. 13. In the example of FIG. 13, each AC box 700 is connected toan AC/DC power supply 600 (first power supply device) for supplyingpower to the device load #1 and an AC/DC power supply 600 (second powersupply device) for supplying power to the device load #2, and each AC/DCpower supply 600 is provided with the current balancing circuit 620 forequalizing the outputs of the AC/DC power supplies 600. For example, incase where the breaker 710 of the AC box #4 trips and thereby powersupply from the AC box #4 is interrupted, power supply from the AC/DCpower supply #14 to the device load #1 and power supply from the AC/DCpower supply #24 to the device load #2 are interrupted. In this state,the current consumption 30 A of the device load #1 has to be covered byremaining three AC/DC power supplies #11, #12 and #13, and the currentconsumption 30 A of the device load #2 has to be covered by remainingthree AC/DC power supplies #21, #22 and #23. Since each AC/DC powersupply 600 is provided with the current balancing circuit 620, thecurrent consumption to be covered by each AC/DC power supply 600 becomes10 A. Since each AC box #1-#3 supplies power to two AC/DC power supplies600, power supply to the disk array device 100 can be maintainedavoiding interruption by implementing each AC box #1-#3 (700) by onecapable of withstanding at least 20 A. While interruption of powersupply from the AC box #4 has been taken as an example, other cases(interruption of power supply from AC box #1, #2 or #3) are similar tothe above case and thus description thereof is omitted for brevity.

As above, the disk array device 100 of this embodiment is capable ofavoiding the increase of current-carrying capacity of the AC boxes 700and the power switchboard 1100 even when the current consumptionincreases due to scaling up of the disk array device 100, by which theneed of electrical work to the facilities and modification of theelectric power contract can be eliminated and thereby costs and load onthe user for the installation of the disk array device 100 can bereduced.

Further, in the disk array device 100 of this embodiment, each AC box700 is connected to an AC/DC power supply 600 supplying power to thedevice load #1 and an AC/DC power supply 600 supplying power to thedevice load #2. Therefore, the AC/DC power supplies 600 and AC boxes 700can be increased or decreased flexibly depending on the scale of thedisk array device 100. For example, in the example of FIG. 13, the ACbox #4 (for supplying power to the AC/DC power supplies #14 and #24) canbe added to the disk array device 100 at the point when the AC/DC powersupplies #14 and #24 (marked as “option”) are added to the device loads#1 and #2 respectively. Thus, by the embodiment, a disk array device 100of a scale meeting the user's needs can be provided to the user whileproviding the disk array device 100 with the power supply matching thescale.

Further, the ratio among the currents passing through the AC boxes 700can be changed by inputting the balance setting signal to the currentbalancing circuit 620 of each AC/DC power supply 600, by which flexibleand suitable power supply can be realized depending on the power supplyequipment of the user. For example, it is also possible to let the diskarray device 100 of this embodiment receive power supply by use of threeAC boxes 700 as shown in FIG. 14.

In the example of FIG. 14, in case where the breaker 710 of the AC box#1 trips and thereby power supply from the AC box #1 is interrupted forexample, power supply from the AC/DC power supplies #11 and #13 to thedevice load #1 and power supply from the AC/DC power supplies #21 and#23 to the device load #2 are interrupted. In this state, the currentconsumption 30 A of the device load #1 has to be covered by remainingtwo AC/DC power supplies #12 and #14, and the current consumption 30 Aof the device load #2 has to be covered by remaining two AC/DC powersupplies #22 and #24. Since each AC/DC power supply 600 is provided withthe current balancing circuit 620, the current consumption to be coveredby each AC/DC power supply 600 becomes 15 A. Since each AC box #2, #3supplies power to two AC/DC power supplies 600, power supply to the diskarray device 100 can be maintained avoiding interruption by implementingeach AC box #2, #3 (700) by one capable of withstanding at least 30 A.

Meanwhile, in case where the breaker 710 of the AC box #3 trips andthereby power supply from the AC box #3 is interrupted for example,power supply from the AC/DC power supply #14 to the device load #1 andpower supply from the AC/DC power supply #24 to the device load #2 areinterrupted. In this state, the current consumption 30 A of the deviceload #1 has to be covered by remaining three AC/DC power supplies #11,#12 and #13, and the current consumption 30 A of the device load #2 hasto be covered by remaining three AC/DC power supplies #21, #22 and #23.Since each AC/DC power supply 600 is provided with the current balancingcircuit 620, the current consumption to be covered by each AC/DC powersupply 600 becomes 10 A. Since the AC box #1 supplies power to fourAC/DC power supplies 600, power supply to the disk array device 100 canbe maintained avoiding interruption by implementing the AC box #1 (700)by one capable of withstanding at least 40 A. Meanwhile, since the ACbox #2 supplies power to two AC/DC power supplies 600, power supply tothe disk array device 100 can be maintained avoiding interruption byimplementing the AC box #2 (700) by one capable of withstanding at least20 A. Interruption of power supply from the AC box #2 is similar to theabove case and thus explanation thereof is omitted for brevity.

As above, in the example of FIG. 14, by employing the AC box #1 that canwithstand at least 40 A and the AC boxes #2 and #2 that can withstand atleast 30 A, the interruption of power supply to the disk array device100 can be avoided even in case of interruption of power supply from anAC box 700.

Incidentally, it is also possible to provide the current balancingcircuit 620 to each AC box 700 and equalize output currents of the ACboxes 700 as shown in FIG. 17. The equalization of the output currentsof the AC boxes 700 makes it possible to employ the same AC boxes(withstanding at least 30 A) for all the AC boxes #1-#3 in the exampleof FIG. 14.

Concretely, in the case where the breaker 710 of the AC box #1 trips andthereby power supply from the AC box #1 is interrupted, power supplyfrom the AC/DC power supplies #11 and #13 to the device load #1 andpower supply from the AC/DC power supplies #21 and #23 to the deviceload #2 are interrupted. In this state, the current consumption 30 A ofthe device load #1 has to be covered by remaining two AC/DC powersupplies #12 and #14, and the current consumption 30 A of the deviceload #2 has to be covered by remaining two AC/DC power supplies #22 and#24. In this case, the AC/DC power supplies #12 and #22 are fed by theAC box #2 and the AC/DC power supplies #14 and #24 are fed by the AC box#3, and thus a current of 30 A passes through each of the AC boxes #2and #3 and a current of 15 A passes through each of the AC/DC powersupplies #12, #22, #14 and #24. Therefore, power supply to the diskarray device 100 can be maintained avoiding interruption by implementingeach AC box #2, #3 (700) by one capable of withstanding at least 30 A.

Meanwhile, in the case where the breaker 710 of the AC box #3 trips andthereby power supply from the AC box #3 is interrupted, power supplyfrom the AC/DC power supply #14 to the device load #1 and power supplyfrom the AC/DC power supply #24 to the device load #2 are interrupted.In this state, the current consumption 30 A of the device load #1 has tobe covered by remaining three AC/DC power supplies #11, #12 and #13, andthe current consumption 30 A of the device load #2 has to be covered byremaining three AC/DC power supplies #21, #22 and #23. In this case, theAC/DC power supplies #11, #13, #21 and #23 are fed by the AC box #1,while the AC/DC power supplies #12 and #22 are fed by the AC box #2.Since each AC box #1, #2 is provided with the current balancing circuit620, each of the AC/DC power supplies #11, #13, #21 and #23 fed by theAC box #1 outputs a current of 7.5 A, while each of the AC/DC powersupplies #12 and #22 fed by the AC box #2 outputs a current of 15 A.Therefore, power supply to the disk array device 100 can be maintainedavoiding interruption by implementing each AC box #1, #2 (700) by onecapable of withstanding at least 30 A.

As described above, by the disk array device 100 according to theembodiment of the present invention, the increase of current-carryingcapacity of the AC boxes 700 and the power switchboard 1100 can beavoided even if the current consumption of the disk array device 100increases for scaling up. In other words, the number andcurrent-carrying capacity of the AC boxes 700 of the disk array device100 can be set suitably in combination depending on the number ofoutlets of the power supply equipment of the place where the disk arraydevice 100 is installed and current-carrying capacity of each outlet.Therefore, even in places where power supply equipment of lowcurrent-carrying capacity is only available, the disk array device 100can be installed without the need of modifying each power supplyequipment. In this case, the required current-carrying capacity of eachAC box 700 can be reduced by increasing the number of AC boxes 700 to anoptimum number, not by successively doubling the number of AC boxes 700of the disk array device 100.

Further, in the disk array device 100 of this embodiment, the reductionof the current-carrying capacity can be realized by use of at leastthree AC boxes 700 by employing the current balancing circuits 620, bywhich the need of electrical work to the facilities and modification ofthe electric power contract can be eliminated and thereby costs and loadon the user for the installation of the disk array device 100 can bereduced. In addition, the current balancing circuit 620 also suppressesfluctuations of current passing through each AC box 700, by which thecurrent-carrying capacity of each AC box 700 can be set almost equal tothe current actually passing through the AC box 700. Therefore, thecurrent-carrying capacity of each AC box 700 can be reduced almost tothe actual current consumption.

In the disk array device 100 of this embodiment, by use of three or moreAC boxes 700, the current passing through each AC box 700 can beprevented from exceeding half the current consumption of the disk arraydevice 100 even in case of failure occurring to an AC box 700, by whichthe current-carrying capacity of each AC box 700 can be set small. Inthis case, power supply to the disk array device 100 can be continued bythe remaining AC boxes 700, by which reliability of the disk arraydevice 100 can be improved.

The reduction of the current-carrying capacity of the AC boxes 700enables miniaturization of the AC boxes 700 and downsizing of the diskarray device 100.

While particular illustrative embodiments have been described above forfacilitating the understanding of the present invention, the presentinvention is not to be restricted by those embodiments but only by theappended claims. It is to be appreciated that those skilled in the artcan change or modify the embodiments without departing from the scopeand spirit of the present invention and such equivalents are included inthe present invention.

1. A storage system, comprising: a channel adapter coupled to a hostcomputer and receiving a read/write command sent from the host computer;a memory coupled to the channel adapter and storing data transferredfrom the channel adapter; a disk adapter coupled to the memory andtransferring data stored in the memory to a plurality of storageregions; a plurality of disk drive units having the storage regions andstoring data transferred from the disk adapter; at least one DirectCurrent (DC) power supply device supplying DC power to at least one loadand having plural phases of Alternate Current Direct Current (AC-DC)converters and a current balancing circuit; and at least one AlternateCurrent (AC) unit having at least one breaker, which breaker interruptssupply of AC power if AC power exceeds a certain level, and receiving ACpower supplied from outside and supplying AC power to the DC powersupply device, wherein the load includes the channel adapter, thememory, the disk adapter or the disk drive units, and wherein thecurrent balancing circuit balances DC power supplied from the pluralphases of AC-DC converters.
 2. A storage system according to claim 1wherein the plural phases of AC-DC converters are three phases of AC-DCconverters.
 3. A storage system according to claim 1, wherein the ACunit has a plurality of the breakers, wherein a first breaker of thebreakers relates to a first phase of the plural phases of AC-DCconverters, and wherein a second breaker of the breakers relates to asecond phase of the plural phases of AC-DC converters.
 4. A storagesystem according to claim 1, wherein each of at least three AC units isthe AC unit, and wherein at least three AC power supplied from outsideeach is the AC power supplied from outside and each AC power suppliedfrom outside is supplied to one of the AC units.
 5. A storage systemaccording to claim 1, wherein each of a plurality of AC power supplydevices each is the DC power supply device, wherein a plurality of DCunits each is the AC unit, and wherein the DC power supply devices andthe AC units are connected by at least one power subtly line.
 6. Astorage system according to claim 1, wherein the DC power supply deviceand the AC unit are connected by at least one power supply line.
 7. Astorage system according to claim 1, wherein the channel adapter has aDC-DC converter, wherein the memory has a DC-DC converter, wherein thedisk adapter has a DC-DC converters, and wherein each of the disk driveunits has a DC-DC converter.
 8. A storage system according to claim 1,wherein a plurality of DC power supply devices each is the DC powersupply device, wherein a plurality of AC units each is the AC unit,wherein a first AC unit of the AC units relates to a first DC powersupply device of the DC power supply devices, and wherein a second ACunit of the AC units relates to a second DC power supply device of theDC power supply devices.
 9. A storage system according to claim 1,wherein a plurality of DC power supply devices each is the DC powersupply device, wherein a plurality of AC units each is the AC unit,wherein a first AC unit of the AC units corresponds to a first pluralityof DC power supply devices of the DC power supply devices, and wherein asecond AC unit of the AC units corresponds to a second plurality of DCpower supply devices of the DC power supply devices.
 10. A storagesystem according to claim 1, wherein a plurality of DC power supplydevices each is the DC power supply device, and wherein DC powersupplied from each of the DC power supply devices is controlled to beapproximately equal.
 11. A storage system according to claim 1, whereineach of a plurality of DC power supply devices is the DC power supplydevice, and wherein the relationship between DC power outputted from afirst DC power supply device of the DC power supply devices and DC poweroutputted from a second DC power supply device of the DC dower supplydevices is controlled to be to approximately a certain ratio.
 12. Astorage system according to claim 1, wherein a plurality of DC powersupply devices each is the DC power supply device, wherein each of theDC power supply devices having a current balancing circuit for balancingDC power supplied from the each of DC power supply devices, and whereina plurality of the current balancing circuits communicate to each othervia at least one communication line.
 13. A storage system according toclaim 1, wherein a plurality of AC units each is the AC unit, whereineach of the AC units has a current balancing circuit for balancing ACpower output from the each of AC units, and wherein a plurality of thecurrent balancing circuits communicate with each other via at least onecommunication line.
 14. A storage system, comprising: a channel adaptercoupled to a host computer and receiving a read/write command sent fromthe host computer; a memory coupled to the channel adapter and storingdata transferred from the channel adapter; a disk adapter coupled to thememory and transferring data stored in the memory to a plurality ofstorage regions; a plurality of disk drive units having the storageregions and storing data transferred from the disk adapter; at least oneDirect Current (DC) power supply device supplying DC power to at leastone load and having plural phases of AC-DC converters; a currentbalancing circuit balancing DC power supplied from the plural phases ofAC-DC converters; and at least one Alternate Current (AC) unit having atleast one breaker, which breaker interrupts to supply AC power if ACpower exceeds a certain level, and receiving AC power supplied fromoutside and supplying AC power to the DC power supply device, whereinthe load includes the channel adapter, the memory, the disk adapter orthe disk drive units.
 15. A storage system, comprising: a channeladapter coupled to a host computer and receiving a read/write commandsent from the host computer; a memory coupled to said channel adapterand stoning data transferred from the channel adapter; a disk adaptercoupled to the memory and transferring data stored in the memory to aplurality of storage regions; a plurality of disk drive units having thestorage regions and storing data transferred from the disk adapter; atleast one Direct Current (DC) power supply device supplying DC power toat least one load and having plural phases of AC-DC converters; acurrent balancing circuit balancing DC power supplied from the pluralphases of AC-DC converters; and at least one Alternate Current (AC)inputs AC power to the DC power supply device, wherein the load includesthe channel adapter, the memory, the disk adapter or the disk driveunits.
 16. A storage system, comprising: a channel adapter coupled to ahost computer and receiving a read/write command sent from the hostcomputer; a memory coupled to the channel adapter and storing datatransferred from the channel adapter; a disk adapter coupled to thememory and transferring data stored in the memory to a plurality ofstorage regions; a plurality of disk drive units having the storageregions and storing data transferred from the disk adapter; at least oneAlternate Current-Direct Current (AC-DC) power supply device supplyingDC power to at least one load and having plural phases of AC-DCconverters; and at least one AC unit supplying AC power to the AC-DCpower supply device, wherein the load includes the channel adapter, thememory, the disk adapter or the disk drive units, and wherein DC powersupplied from the plural phases of AC-DC converters are balanced.